Conventionally, various printing plates for planographic printing without using dampening water utilizing a silicone rubber or fluorine resin as an ink repellent layer, particularly photosensitive waterless planographic printing plates prepared by selective exposure and development are proposed.
For example, there is a positive photosensitive waterless planographic printing plate with a photo-polymerizable adhesive layer and an ink repellent silicone rubber layer laminated on a substrate.
Furthermore, a waterless planographic printing plate with a photo merizable aphotosensitive layer and an ink repellent silicone rubber layer laminated on a substrate is also proposed. For developing them, JP-B-63-21890, etc. describe a development method using a propylene oxide derivative and a hydrocarbon, and JP-B63-33140, etc. describe a development method using water.
Moreover, JP-A-59-17552 discloses a method for obtaining a waterless planographic printing plate of either negative or positive type by treatment with a base of an image forming laminate in which a photosensitive layer composed of a material containing a quinonediazide structure and a silcone rubber layer are laminated in this order on a substrate. This patent specification also describes a method for obtaining negative and positive waterless planographic printing plates from one plate material wider in development latitude such as image reproducibility, solvent resistance and developability. The treatment method with a base described in it is to use an inorganic base and/or an organic base as a gas or liquid, and in the case of liquids it is described to use water or any publicly known organic solvent as a solvent.
JP-A-60-169852 discloses a method comprising the steps of exposing to an image, developing, fully exposing and treating by a base for fixing. Furthermore, JP- A-62-294246 describes the use of a polar solvent and an aminoalkanol as a treating liquid, and JP-A-63-201657, the use of a polar solvent, an alkoxyalkylamine, etc.
The treating liquids for making waterless planographic printing plates in these prior arts have such a problem that when a positive waterless planographic printing plate with a photo-polymerizable adhesive layer is used in an automatic developing machine, the developability fluctuates due to the evaporation of the hydrocarbon used or the absorption of water by the treating liquid. As a method for overcoming these disadvantages, JP-A-5-34931 proposes immersing in a treating liquid containing an alkylene carbonate before development by water.
In the case of a waterless planographic printing plate using a photosensitive layer composed of a material containing a quinonediazide structure, a base treating solution composed of an organic solvent and an organic base such as an amine is preferably used. However, if it is used in an automatic developing machine, its use for a long period of time is disadvantageous because the treating solution is poor in stability due to decline of amine concentration, etc.
As a method for overcoming these disadvantages, JP-A-63-179361 proposes a treating liquid containing a monoamine with ethylene oxide or propylene oxide added.
However, this method has a disadvantage in that when a waterless planographic printing plate with a silicone rubber layer as the uppermost layer is coated with a treating liquid by a spray, brush or pad, etc.. a good image reproducibility cannot be obtained because the coatability on the plate surface is poor and uneven and because the treating liquid is poor in stability. So, a treating liquid for making a waterless planographic printing plate, which is good in stability, excellent in coatability and developability and large in the effect of treatment with a base, is demanded.